1. Field of the Invention
This invention relates to a panel structure of a surface-discharge-type alternating-current plasma display panel.
The present application claims priority from Japanese Application No. 2002-30297, the disclosure of which is incorporated herein by reference for all purposes.
2. Description of the Related Art
At the present time, AC matrix plasma display panels using a gas discharge for producing light emission (hereinafter referred to as xe2x80x9cPDPxe2x80x9d) have been released on the market as an oversized and slim display for color screen, and attempts have also been made to become commonly used in ordinary homes and the like.
FIG. 6 to FIG. 8 are schematic views of a conventional construction of the surface-discharge-type alternating-current plasma display panel. FIG. 6 is a front view of the conventional surface-discharge-type AC plasma display panel. FIG. 7 is a sectional view taken along the Vxe2x80x94V line of FIG. 6. FIG. 8 is a sectional view taken along the Wxe2x80x94W line of FIG. 6.
In FIGS. 6 to 8, the plasma display panel (hereinafter referred to as xe2x80x9cPDPxe2x80x9d) includes a front glass substrate 1, serving as the display surface of the PDP, having on its back surface, in order, a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2), a dielectric layer 2 covering the row electrode pairs (Xxe2x80x2, Yxe2x80x2), and a protective layer 3 made of MgO and covering the back surfaces of the dielectric layer 2.
Each of the row electrodes Xxe2x80x2, Yxe2x80x2 is constructed of a transparent electrode Xaxe2x80x2, Yaxe2x80x2 which is formed of a transparent conductive film with a larger width made of ITO or the like, and a bus electrode Xbxe2x80x2, Ybxe2x80x2 which is formed of a metal film with a smaller width assisting the electrical conductivity of the corresponding transparent electrode.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are arranged in alternate positions in the column direction such that the electrodes Xxe2x80x2 and Yxe2x80x2 of each pair (Xxe2x80x2, Yxe2x80x2) face each other with a discharge gap gxe2x80x2 in between. Each of the row electrode pairs (Xxe2x80x2, Yxe2x80x2) forms a display line (row) L in the matrix display.
The front glass substrate 1 is situated opposite a back glass substrate 4 with a discharge-gas-filled discharge space Sxe2x80x2 interposed between the substrates 1 and 4. The back glass substrate 4 is provided thereon with: a plurality of column electrodes Dxe2x80x2 which are arranged in parallel to each other and each extend in a direction at right angles to the row electrode pair (Xxe2x80x2, Yxe2x80x2); band-shaped partition walls 5 each extending in parallel to and between adjacent column electrodes Dxe2x80x2; and phosphor layers 6 formed of phosphor materials of a red color, green color, and blue color, each of which covers the side faces of adjacent partition walls 5 and the column electrode Dxe2x80x2.
In each display line L, the partition walls 5 partition the discharge space Sxe2x80x2 into areas each corresponding to an intersection of the column electrode Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2), to define discharge cells Cxe2x80x2 which are unit light-emitting areas.
Such surface-discharge-type alternating-current PDP generates images through the following procedure.
First, in an addressing period following a reset period for carrying out a reset discharge, a discharge (an addressing discharge) is selectively caused between one row electrode of each electrode pair (Xxe2x80x2, Yxe2x80x2) (the row electrode Yxe2x80x2 in this example) and the column electrode Dxe2x80x2 in each of the discharge cells Cxe2x80x2. As a result of the addressing discharge, lighted cells (the discharge cell in which wall charges are generated on the dielectric layer 2) and non-lighted cells (the discharge cell in which wall charges are not generated on the dielectric layer 2) are distributed over the panel surface in accordance with an image to be displayed.
After completion of the addressing period, a discharge sustaining pulse is applied alternately to the row electrodes Xxe2x80x2 and Yxe2x80x2 of each row electrode pair simultaneously in each display line L. Every time the discharge sustaining pulse is applied, a discharge (a sustaining discharge) is caused between the row electrodes Xxe2x80x2 and Yxe2x80x2 in each lighted cell by the wall charges generated on the dielectric layer 2.
Ultraviolet light is generated by the sustaining discharge in each lighted cell, which then excites the red, green or blue phosphor layer 6 in each discharge cell Cxe2x80x2 to thereby form a display image.
In the conventional three-electrode surface-discharge-type alternating-current PDP having an arrangement of the row electrodes Xxe2x80x2 and Yxe2x80x2 in alternate positions in the column direction as described above, a potential difference is produced between the back-to-back positioned row electrodes Xxe2x80x2 and Yxe2x80x2 (between the back-to-back bus electrodes Xbxe2x80x2 and Ybxe2x80x2) of the respective row electrode pairs (Xxe2x80x2, Yxe2x80x2) adjacent to each other when the PDP is driven, and capacitance occurs in the non-display area between the back-to-back positioned row electrodes Xxe2x80x2 and Yxe2x80x2.
The potential difference produced between the back-to-back positioned bus electrodes Xbxe2x80x2 and Ybxe2x80x2 in this manner becomes a cause of creating an undesired surface discharge between the bus electrodes Xbxe2x80x2 and Ybxe2x80x2. Further, the capacitance formed in the non-display area between the corresponding display lines L becomes a cause of an increase of unnecessary power consumption.
In order to reduce such unnecessary power consumption which occurs in the non-display area between adjacent display lines L, making sufficient spacing between the back-to-back bus electrodes Xbxe2x80x2 and Ybxe2x80x2 is needed.
However, increasing the spacing between the back-to-back bus electrodes Xbxe2x80x2 and Ybxe2x80x2 results in an increase in area of the non-display area in the established entire display area of the PDP.
Accordingly, maintaining the same number of display lines L produces a problem of a reduction in brightness because of a decrease in area of the opening of each discharge cell Cxe2x80x2 by an increased amount of area of the non-display area, whereas maintaining the area of an opening of each discharge cell Cxe2x80x2 produces another problem of impossibility of increasing an image definition because the number of display lines L is decreased.
The present invention has been made to solve the above problems associated with the prior art surface-discharge-type alternating-current plasma display panels.
Accordingly, it is an object of the present invention to provide a surface-discharge-type alternating-current plasma display panel which is capable of reducing unnecessary power consumption occurring in a non-display area between adjacent display lines without a reduction in the number of display lines and in brightness.
To attain this object, according to a first feature of the present invention, a plasma display panel including: a pair of substrates opposite each other with an interposed discharge space; a plurality of row electrode pairs provided on an inner surface of one substrate of the pair of the substrates, arranged in a column direction and each extending in a row direction to form a display line; a dielectric layer covering the row electrode pairs on the inner surface of the one substrate; and a plurality of column electrodes provided on a surface of the other substrate facing the one substrate, arranged in the row direction, and each extending in the column direction to intersect the row electrode pairs and form unit light-emitting areas in the discharge space at the respective intersections, the plasma display panel comprises: a recess provided in a portion of the inner surface of the one substrate facing a non-display area between the adjacent unit light-emitting areas in the column direction, wherein each of row electrodes constituting each of the row electrode pairs comprises an edge portion, and the adjacent edge portions of the respective row electrodes positioned back to back in between the adjacent row electrode pairs respectively extend along both side faces of each of the recesses, formed in the one substrate, in a direction of raising the edge portions in relation to other portions of the respective row electrodes concerned in a thickness direction of the one substrate.
In the plasma display panel according to the first feature, the edge portion of each of the row electrodes constituting the row electrode pair is formed to extend along a side face of the recess within each of the recesses, formed in the inner surface of one of the substrate with the row electrode pairs formed thereon, in such a way as to raise the edge portion in relation to another portion of the row electrode concerned in a thickness direction of the one substrate. Hence, spacing between the edge portions of the respective row electrodes adjacent to each other with the interposed recess is increased by a surplus area created by providing the edge portion of the row electrode in the raised position, as compared with the prior art PDPs having the same number of display lines and the same opening area of the unit light-emitting area as those in the PDP of the present invention.
Therefore, after completion of an addressing discharge produced between the column electrode and one row electrode of the row electrode pair, a discharge sustaining pulse is applied alternately to the row electrodes of the row electrode pair to cause a sustaining discharge between the row electrodes. In this sustaining discharge, if even a potential difference is produced between the row electrodes positioned back to back in between the adjacent row electrode pairs, a discharge is prevented from occurring between the adjacent edge portions of the respective row electrodes concerned and also capacitance between the edge portions concerned is decreased, because of the adequately opened spacing between the edge portions concerned.
According to the first feature, the present invention allows prevention of occurrence of undesired power consumption without a reduction in the number of display lines and in the area of an opening of each unit light-emitting area.
Further, when the spacing between the edge portions of the back-to-back positioned row electrodes is established to be equal to that in the prior art PDPs, it is possible to reduce a pitch of the spacing between the display lines to increase the number of display lines for higher image definition and also to increase the area of the opening of each unit light-emitting area to increase image brightness.
To attain the aforementioned object, the plasma display panel according to the present invention has, in addition to the configuration of the first feature, a second feature that each of the row electrodes constituting each of the row electrode pairs comprises an electrode body extending in the row direction and forming the edge portion, and transparent electrodes each extending from the electrode body in the column direction to face the other row electrode of the paired row electrodes with an interposed discharge gap, and that the electrode body extends along one of the both side faces of the recess in a direction of raising the electrode body in relation to the corresponding transparent electrode in a thickness direction of the one substrate.
In the plasma display panel according to the second feature, the electrode body of the row electrode is formed to extend along a side face of the recess within the recess formed in the inner surface of the one substrate in such a way as to raise the electrode body in relation to the corresponding transparent electrode of the row electrode in the thickness direction of the one substrate. Hence, the spacing between the adjacent electrode bodies of the respective row electrodes positioned back to back in between the adjacent row electrode pairs is increased as compared with the prior art PDPs.
Due to this design, if even a potential difference is produced between the electrode bodies positioned back to back in between the adjacent row electrode pairs when a sustaining discharge is caused, a discharge is prevented from occurring between the electrode bodies concerned. Additionally, capacitance between the electrode bodies concerned is decreased, thereby preventing occurrence of undesired power consumption.
To attain the aforementioned object, the plasma display panel according to the present invention has, in addition to the configuration of the first feature, a third feature of further comprising a middle layer provided on a portion of the inner surface of the one substrate facing each of the unit light-emitting areas to be interposed between the one substrate and the dielectric layer, wherein each of the recesses is configured by a space between the middle layers adjacent to each other in the column direction, and each of the row electrode pairs is formed on the middle layer.
According to the third feature, the middle layer is formed on a portion of the inner surface of the one substrate facing each of the unit light-emitting areas by means of the patterned coating of a photosensitive glass paste by the use of photolithographic techniques or the like, for example. Then, the row electrode pair and the dielectric layer are formed on the middle layer.
Between the adjacent middle layers in the column direction, the recess is formed to face the non-light emitting area, and the edge portion of the row electrode is formed to extend along the side face of the recess in such a way as to the edge portion in relation to another portion of the row electrode concerned in the thickness direction of the one substrate.
To attain the aforementioned object, the plasma display panel according to the present invention has, in addition to the configuration of the first feature, a fourth feature that the recess is formed by partially cutting the inner surface of the one substrate.
According to the fourth feature, the inner surface of the one substrate is cut at portions each facing the non-display area between the adjacent unit light-emitting areas in the column direction to form the recesses.
Each of the row electrode pairs is formed on the portion of the inner surface of the one substrate facing each unit light-emitting area. Each of the adjacent edge portions of the respective row electrodes positioned back to back in between the adjacent row electrode pairs in the column direction extends along the side face of the recess in such a way as to raise the edge portion in relation to another portion of the same row electrode in the thickness direction of the one substrate.
To attain the aforementioned object, the plasma display panel according to the present invention has, in addition to the configuration of the first feature, a fifth feature that the both side faces of the recess extend in a direction approximately perpendicular to the one substrate.
According to the fifth feature, each of the side faces of the recess is formed to extend in a direction approximately perpendicular to the one substrate. That is to say, the recess is shaped to be approximately rectangular in cross section. Then, the edge portion of one row electrode adjacent to another row electrode of a different row electrode pair is formed to extend along one of the inner side faces of the recess which is parallel to the thickness direction of the one substrate. Thus, a mounting area of the edge portion of the row electrode when viewed from the surface of the one substrate on the display surface side is further decreased, so that the spacing between the edge portions of the back-to-back row electrodes is increased by a decreased area of the mounting area.
With such design, the effectiveness of prevention of a discharge from occurring in the non-display area is enhanced. Additionally, capacitance between the edge portions of the back-to-back row electrodes is also decreased much more, leading to effective prevention of occurrence of undesired power consumption.
To attain the aforementioned object, the plasma display panel according to the present invention has, in addition to the configuration of the first feature, a sixth feature that the side faces of both sides of the recess respectively extend along indented faces of the one substrate in a wedge-like form.
According to the sixth feature, the recess has the two side faces formed in a configuration resulting from indenting the one substrate in wedge-like form. In other words, the recess is shaped to be approximately trapezoidal in cross section so as to gradually increase in width toward the top of the trapezoid. Accordingly, the spacing between the adjacent edge portions of the respective row electrodes formed along the corresponding side faces of the recess increases gradually toward the top of the recess. This design improves the effectiveness of prevention of occurrence of a discharge in the non-display area, and also a further decrease in capacitance between the edge portions of the back-to-back row electrodes, leading to more effective prevention of unnecessary power consumption.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.